Five year-old Grace Kennedy cools off from the heat in a water fountain in Stinson Park in Omaha, Neb. An unusual, late-summer heat wave enveloped much of the Midwest, putting schools and sports events on hold. Some schools in Iowa, Nebraska, Wisconsin, the Dakotas and Illinois let out early as temperatures crept toward the mid-90s, and beyond in some places. (ASSOCIATED PRESS / Nati Harnik)

LINCOLN, Neb. (AP) — Popsicles, fans and outdoor classes were no match for a late-summer heat wave in Minneapolis, where schools finally gave up after struggling through three miserable days of classes, while soaring temperatures also were giving students time off in Colorado, Nebraska and Iowa.

Minnesota's largest school district called off classes Thursday and Friday in 27 buildings that lack much or any air conditioning. The decision came after days of complaints from teachers and some parents about difficult learning conditions as temperatures hovered in the upper 90s with high humidity.

"We tried to have school and get off to a good, quality start here," spokeswoman Rachel Hicks said, adding that the persistent heat was taking a toll on students and staff. "The decision really came down to the consecutive days of heat."

Classes were to resume Tuesday after the Labor Day holiday, and students won't have to make up the time.

Schools in and around Fort Collins, about 60 miles north of Denver, also will be closed because of the heat on Friday. Denver Public Schools said schools on its West Campus would release students at noon Friday due to extreme heat and that schools without air conditioning could decide to do the same.

Students are being released early all week in Eagle Grove, Iowa, where window air conditioners in the 1920s-era school simply couldn't keep up, Superintendent Jeff Toliver said.

"The hallways and gym are going to be 85 degrees, even without the students," said Toliver, who oversees about 800 students. "You get all of that hot, stale air, and then you bring kids into the room. My feeling is that's not a very good educational environment."

In the south-central Nebraska town of Hastings, students have been dismissed early each day for the last two weeks because of the heat, said Trent Kelly, the school district's technology and operations director. Three of the district's six elementary schools have classrooms with no air conditioning, so administrators placed industrial-sized fans in doorways to draw in cooler, morning air.

Some teachers were holding class in air-conditioned gymnasiums. Kelly said the temperature in one second-floor classroom climbed to 91 degrees.

"I've been here 12 years, and I don't remember ever doing (early dismissals) for this long a period," Kelly said. "But this is Nebraska. It's going to be hot."

In Colorado, the Downtown Denver Expeditionary School made attendance optional on Thursday, and the charter school planned to be closed Friday because temperatures are once again predicted to be in the 90s. Denver Public Schools has dozens of buildings without air conditioning, with some built more than 100 years ago.